Quote:
Originally Posted by jss06c6
So far, I have not seen any limitations presented by the OEM ECM. OBDII controls are a bit richer, but the ECM in the LT-5 is definitely state of the art for the time it was introduced. Managing effectively two tunes, real time, is a testament to the engineers that put this engine in the market..
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(Emphasis mine.)
Hear, hear!
These 2 power/torque curves certainly had different calibration requirements. Same engine, Port Throttles Open vs. Port Throttles Closed.
(dyno graph supplied by Graham Behan)
As you can see, she gets a bit wheezy with the Power Key Turned to Reduced/Normal from Full. Cuts down over 225 crank hp @ 6500rpm
Yes the ECMs ability to switch from 8 injectors to 16 and to keep up with the variable geometry plenum were simply amazing for 1980s technology.
Going from 16 injectors down to 8 required a TPS % zero out IIRC, at least in the OEM cals. The LT5 was a huge step coming out of the performance doldrums of the 1970s and early 80's when 3221 1980 Corvettes were available with a 180hp@4200/255lb/ft@2000rpm SAE net hp LG4 305 "gasp" with 8.5:1c/r(and a $50 rebate for such a necessity-the L48 350 made 190hp@4200rpm/280lb/ft@2400rpm with 8.2:1 c/r, the L82 made 230hp@5200rpm/ 275lb/ft torque@3600rpm with 9.0:1c/r).
So I'd agree with you and say that more than doubling the output of the engine, in less than 10 model years of a car, without using forced induction, while still maintaining emissions and still pulling a 16/25 MPG rating, is certainly an amazing engineering feat. It must have been an exciting time to be an Engineer at Lotus. or any other manufacturer.
Being able to report SAE net ratings of 375hp@6000rpm and 405hp @5800rpm and then develop the 3rd iteration of the LT5 with numbers over 525hp@7200rpm must have been a satisfying "days work".
It would take the Chev guys well over 10 years to get over 500hp into a N/A car with the 2006 LS7 and its SAE Certified 505hp@6300rpm/470 lb/ft @4700rpm, but into a car the GEN 4 LS7 went. I so wish the GEN 3 LT5 went into a C5, with the Lotus C5 powebulge hood and all.